Place the cut side of the onion up in a third bowl. Sprinkle flour mixture over onion until completely coated. Turn onion over carefully to shake excess flour off.
Pour egg mixture over and let sit for a minute. Again, turn onion over to remove excess egg mixture.
Pour the flour mixture on onion again. Turn over to remove excess flour.
Put into air fryer basket and spray generously.
Cook at 350 degrees F for approximately 15 to 20 minutes. Keep spraying as you keep checking the onion.